1. Field
The present disclosure relates to electromagnetic wave generators and optical shutters, and more particularly, to electromagnetic wave generators that may generate wideband electromagnetic waves, including waves having frequencies within the THz band, and which may control wavelengths of output electromagnetic waves, and optical shutters operating in a similar manner as the electromagnetic wave generators.
2. Description of the Related Art
Terahertz electromagnetic waves (hereinafter, referred to as terahertz waves) are electromagnetic waves generally having a frequency within the frequency band of between about 0.1 THz and about 10 THz. The terahertz waves may easily propagate through many materials through which microwaves or light waves may not propagate, and the terahertz wave may also be absorbed by moisture. Therefore, terahertz waves are increasingly being considered important for potential uses in various technical fields, such as medical, chemical, military, biological, environmental, and information communication fields. However, since apparatuses for reliably generating electromagnetic waves in the terahertz band have not been sufficiently developed, research into new terahertz generators is actively being conducted.
For example, certain types of terahertz generators, such as those using a solid state laser having non-linear crystals and terahertz generators of electromagnetic induction type using coils or magnets have been developed. However, the types of terahertz generators that have been developed thus far are limited. For example, these generators may only generate terahertz waves of a certain wavelength, or a usable band of the output terahertz waves may be too narrow to be applied to various fields. For example, terahertz waves of various wavelengths are necessary to perform tomographies of different organs (i.e., heart, blood vessels, stomach, etc.) in the human body, and the conventional terahertz generator may not satisfy this need. In addition, many of the conventional terahertz generators consume an excessive amount of power.